1. Field of the Invention
The present invention relates to a defroster for a heat exchanger and a fabrication method thereof, and more particularly to a defroster for a heat exchanger capable of using an environment-friendly, alternative refrigerant and improving a defrosting performance.
2. Description of the Background Art
In a refrigeration cycle system of the background art, a refrigerant is compressed so as to be in a high temperature-high pressure phase by applying electric energy to a compressor. The compressed, high temperature-high pressure refrigerant is then condensed in a condenser by emitting heat to the outside, and the condensed refrigerant flows into an evaporator through a capillary tube. The evaporator absorbs heat from the outside while the refrigerant is evaporated in the evaporator. In this of refrigeration cycle system, the condenser for emitting heat to the outside or the evaporator for absorbing heat from the outside is referred to as a heat exchanger.
A refrigerator or an air conditioner, etc. preserves food or maintains a temperature of a room in a pleasant state by using a heat exchanger of a refrigeration cycle system. The heat exchanger is often curved so as to have a multiple-shaped refrigerant piping in which a refrigerant flows, and plural heat transfer fins 40 are combined with the curved refrigerant piping in order to increase a heat transfer area. While the refrigerant flows in the refrigerant piping, the heat exchanger exchanges heat with external air through the refrigerant piping and the heat transfer fins 40.
The present inventors have determined that the systems of the background art suffer from the following disadvantages. In the case of a refrigerator or a showcase, etc., a heat exchanger is installed at a side of a food storing space, and a flow of air caused by a fan arranged at a side of the heat exchanger maintains the food storing space in a cold state as it flows or circulates through the heat exchanger. However, during that process, frost caused by moisture in the air forms on the surface of the heat exchanger in the food storing space. The frost will then lower a heat exchange performance of the heat exchanger significantly. Accordingly, a defroster is installed in the system at the heat exchanger in order to periodically remove frost.
FIG. 1 illustrates an example of a defroster of a heat exchanger in accordance with the background art. As depicted in FIG. 1, the heat exchanger includes a plurality of straight pipes 20 installed between two holders 10. In order to connect the straight pipes 20 in a common flow path, each straight pipe 20 is connected by respective curved connection pipes 30. Each of the connection pipes 30 is respectively arranged at both sides of the holders 10. A plurality of heat transfer fins 40 are also combined with the straight pipes 20.
The defroster typically includes a heater 50 installed below the heat transfer fins 40. The heater 50 having a certain length is curved, and both sides of the heater 50 are respectively combined with the holder 10. The heater 50 is installed at an air inlet side of the air flow path in which air flows through the heat exchanger.
The operation of the defroster in the heat exchanger of the background art will be described in greater detail hereinafter. As the heat exchanger is operating, air flows into the heat exchanger by the rotation of a fan (not shown). Heat exchange is performed while the air circulates between the heat transfer fins 40 of the heat exchanger, and the heat-exchanged cold air is discharged out of the heat exchanger. When frost is formed on the heat exchanger as described above, the operation of the heat exchanger is stopped and/or effective heat transfer is significantly reduced. Accordingly, power is supplied to the heater 50, and the heater 50 is heated. Heat generated by the heater 50 is transmitted to the heat exchanger along with the air to remove the frost. Herein, the frost is removed by convection and radiation of the heat generated by the heater.
A defroster having the wire type heater has high stability when experiencing vibration or external impact, great caloric power per unit length, and a surface temperature thereof that is typically very high (not less than 500° C.). However, the wire type defroster can be typically only be used with a non-environment friendly refrigerant. Specifically, when this type of defroster is used with an environment-friendly, alternative refrigerant, ignition risk is very high because of the great caloric power of this type of heater. For example, when using a refrigerant such as a presently used R-134a, ignition risk is low. However, when using an environment-friendly refrigerant such as R600a, etc., ignition risk is very high and the wire type defroster cannot be used.
In addition, since defrosting is performed by heat generated by the heater 50 arranged at a side of the heat exchanger, defrosting is quickly performed only on portions immediately adjacent to the heater 50. Accordingly a lot of time and power consumption are required for defrosting the entire heat exchanger.